Electronic musical instrument

ABSTRACT

Circuit for an electronic musical instrument in which a matrix coupled to a counter is connected through key switches to an OR gate and thence via a common line to a plurality of gate controlled flip flops also controlled by a second matrix which is coupled to the counter. The flip flops control gates which selectively pass audio signals to a speaker; a third matrix resets the flip flops.

' [22] Filed:

United States Patent Obayashi A [54] ELECTRONIC MUSICAL INSTRUMENT [72] inventor: Nobuharu Obayashi, Shizuoka,

Japan [73] Assignee: Kabushiki Knish: Kawai Gakki Seisnkusho, Shizuoka-ken, Japan Jan. 3, 1972 [21] Appl. No.: 215,055

[52] US. Cl. ..84/l.01, 84/1.11, 84/l.l9 [51] Int. Cl. ..G10h 1/00 [58] Field of Search ..84/1.0l, 1.03, 1.17, 1.19

[56] References Cited UNITED STATES PATENTS 3,610,799 10/1971 Watson ..84/l.26X

[451 Oct. 24, 1972 Primary Examiner-Lewis H. Myers Assistant Examiner-U. Weldon Attorney-Eric H. Waters et al.

[57] ABSTRACT Circuit for an electronic musical instrument in which a matrix coupled to a counter is connected through key switches to an OR gate and thence via a common line to a plurality of gate controlled flip. flops also controlled by' a second matrix which is coupled to the counter. The flip flops control gates which selectively pass audio signals to a speaker; a third matrix resets the flip flops.

4 Drawing Figures 7 FIELD OF THE INVENTION This invention relates to electronic musical instruments.

SUMMARY OF THE INVENTION It is an object of the invention to provide an improved electronic musical instrument.

It is a further object of the invention to provide an improved electronic musical instrument in which the connecting of a key switch portion circuit with a control signal circuit and a sound source signal circuit is extremely simplified so that the wiring for the same is greatly facilitated and so that the signal-to-noise ratio is greatly improved.

An instrument of the invention is characterized in that a multiplex counter circuit is provided on its output side with first and second matrix circuits, each of which is so arranged that successively delayed pulse signals may be taken out at its various output terminals,

and in that the output terminals of the first matrix circuit are connected through respective key switches to a single common output conductor. This conductor and the output terminals of the second matrix circuit are connected to a pulse selective circuit so that if any one of the key switches is closed the corresponding gate circuit is opened and the sound source signal is allowed to pass therethrough.

The invention is further characterized in that a third matrix circuit arranged to generate successively delayed pulse signals at its output terminals is provided on the output side of the multiplex counter circuit, and the output terminals of the third matrix circuit are connected to the pulse selective circuit so that, if the closed key switch is opened, the gate circuit is closed and the sound source signal is prevented from passing therethrough.

Some embodiments of this invention will next be explained with reference to the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a circuit diagram of one embodiment of this invention;

FIG. 2. is a chart of output wave forms at various points in the circuit of FIG. 1;

FIG. 3 is a chart of output wave forms for explaining the operation of the circuit of FIG. 1; and

FIG. 4 is a block diagram showing another embodiment of this invention.

DETAILED DESCRIPTION In FIG. 1, element 1 is a multiplex counter circuit, which comprises an astable multivibrator 1a, which serves as a pulse generating source, and two binary circuits lb 8111 lo. Qircuit l goduces at its output terminals A, A, B, B, C, and the pulses shown at I in FIG. 2. Circuits 2 and 3 are first and secc nd matrix circ t iits connected to outputs terminals A, A, B, B, C and C. Each of these circuits 2 and 3 comprises an AND matrix circuit composed of diodes, and is so arranged that positive pulses as shown at II and III in FIG. 2 are produced in successively delayed relationship at respective output terminals (2-1) (2-8) (3-1) (3-8).

The output terminals (2-1) (2-8) are connected through respective key switches K, K, to an OR circuit 4, and the single output conductor 5 thereof and the output terminals (3-1) (3-8) of the second matrix circuit 3 are connected to pulse selective circuit 7. The first matrix circuit 2, the key switches K, K and the OR circuit 4 constitute a key switch relation circuit 6.

The pulse selective circuit 7 comprises flip-flop circuits FF, FF, corresponding to the key switches K, K and AND gates (8-1) (8-8) connected to respective input terminals of the flip-flops for the setting of the flip-flop circuits FF, FF, The output conductor 5 is connected in common to gates (8-1) (8-8) and the output terminals (3-1) (3-8) of the second matrix circuit 3 are connected to these gates in corresponding relationship.

Gate circuits (9-1) (9-8) are connected to the output terminals of the flip-flop circuits FF, FF, of the pulse selective circuit 7. These gate circuits (9-1) (9-8) are interposed in respective output conductors of a sound source signal oscillator 10. These conductors are connected in common to a speaker 12 through an amplifier 11.

If, for example, the second order switch K, of the key switches K, K is closed, the pulse signal II at the second order in FIG. 2, that is, the pulse signal of FIG. 3 (a) is applied through the output conductor 5 to the AND gates (8-1) (8-8) of the pulse selective circuit 7. At the same time, the pulse signal III at the second order in FIG. 2, that is, the pulse signal of FIG. 3(b) is applied fro the second order terminal (3-2) of the second matrix circuit 3 to the second order AND gate (8-2). Accordingly, the second order AND gate (8-2) is opened and an output pulse signal such as shown in FIG. 3(0) is obtained at its output side. This output pulse signal sets the second order flip-flop circuit FF, which produces an output signal as shown in FIG. 3(e) by which the gate circuit (9-2) is opened. Thereby, the sound source signal from the sound source signal oscillater 10, as shown in FIG. 3(f), is allowed to pass and the speaker 12 is operated by the amplifier 11.

Additionally, a third matrix circuit 13 is provided at the output side of the multiplex counter circuit 1. This matrix circuit 13 comprises an OR matrix circuit composed of diodes, and is so arranged that negative pulses can be obtained in successively delayed relationship at its output terminals (13-1) (13-8) as shown at IV in FIG. 2. These output terminals (13-1) (13-8) and the conductors diverging from the output terminals of the AND gates (8-1) (8-8) are connected to respective input terminals for the resetting of the flip-flop circuits FF, FF, through OR gates (14-1) (14-8).

it, thus, the closed key switch K, is opened the pulse signals are not obtained at the output side of the AND gate (8-2), and only the pulse signal from the third matrix circuit 13 passes through the OR gate (14-2). Such a pulse signal as shown in FIG. 3(d) is applied to the flip-flop circuit FF, to reset the same, whereby the output thereof becomes zero and the gate circuit (9-2) is closed. The passing of the sound source signal is thus prevented.

As will be clear from the above explanation, if, for example the first and the eighth key switches K, and K, are simultaneously closed, there takes place a time difference between the first and the eighth gate circuits (9-1) and (9-8) opened by these switches. If, accordingly, it is assumed that the time difference between two sounds which cannot be distinguished by hearing is 8 msec and it is so arranged that eight pulses are generated within 8 msec, the time difference between the first and the eighth gates (8-1) and (9-8) can scarcely be detected and the two sounds are heard as if they were generated simultaneously. In this case, it is necessary that the oscillation frequency of the astable multivibrator 1a constituting part of the multiplex counter circuit 1 be above 500 Hz.

The above instrument circuit has been explained with reference to a case using eight keys. If, for example, the number of the keys is 61, it is required that the number of binary circuits constituting the multiplex counter circuit 1 be 5 and that the first, second and third matrix circuits each have 61 output terminals. In this case, accordingly, the number of the conductors connected between the multiplex counter circuit 1 and the first matrix circuit 2 is 12 and there is only one output conductor. The number of power supply related conductors (not shown) is three, and the number of conductors leading from the key switch relation circuit need only be sixteen in total. In this case, it is required that the oscillation frequency of the astable multivibrator 1a constituting a part of the multiplex counter circuit ll be above 4,000 Hz.

In such a modification as shown in FIG. 4, two additional key switch relation circuits 6' and 6" are provided in parallel with the key switch relation circuit 6, and two additional pulse selective circuits 7 and 7 corresponding thereto are provided in parallel with the pulse selective circuit 7. Three block gate circuits 9, 9' and 9 each comprising 61 gate circuits are provided on the output sides of the pulse selective circuits 7, 7 and 7 In this case, the key switches in the key switch relation circuits 6, 6' and 6" are arranged to be upper key switches, lower key switches and foot key switches, respectively. Circuit is an upper key tone forming circuit, circuit 15' is an upper key tone forming circuit, and circuit 15" is a foot key tone forming circuit.

If, coupler switches (not shown) are provided in the circuits connected between the key switch relation circuits 6, 6' and 6" and the pulse selective circuits '7, 7 and 7 and are properly operated, a coupler effect can be obtained.

It has been usual with conventional electronic musical instruments that the key switch relation circuits used therein require a signal input conductor for each key and therefore 61 signal input conductors are required if there are 61 keys. In such an arrangement, not only is the wiring complicated, but also since the sound source signal flows directly through the signal input conductor a lot of noise is generated.

According to this invention, however, the number of the connecting conductors between the key switch relation circuit and the multiplex counter circuit need only be 12 when, for example, the number of the keys is 61 and the number of power supply related conductors is three and the number of output conductors is only one. Thus, the total number of conductors is only 16, so that the wiring is greatly simplified. The key switch portion circuit can be formed as a printed circuit or as an integrated circuit. The wiring can therefore be easily com letedb sim l conne tin the sameb means of sixte n conducto s Additionly, no SOU1C1 source signal flows through this circuit as only a control signal flows therethrough, so that noise is greatly decreased.

What is claimed is:

1. An electronic musical instrument comprising a multiplex counter circuit having an output side, first and second matrix circuits coupled to said output side and including output terminals, key switches, a single common output for said key switches, the output terminals of the first matrix circuit being connected through respective of said key switches to said single common output conductor, a pulse selective circuit, said output conductor and respective of the output terminals of the second matrix circuit being connected to said pulse selective circuit, said pulse selective circuit having an output side, a plurality of gate circuits corresponding to the key switches being connected to the output side of the pulse selective circuit so that if any of the key switches is closed the corresponding gate circuit is opened, and a sound source signal generator coupled to said gate circuit to pass a signal therethrough.

2. An electronic musical instrument as claimed in claim 1, wherein the pulse selective circuit comprises a plurality of flip-flop circuits connected to respective of the gate circuits, and a plurality of AND gates connected to and supplying inputs to the flip-flop circuits, said common output conductor being connected to the said AND gates, the output terminals of the second matrix circuit being connected to the AND gates in corresponding relationship.

3. An electronic musical instrument as claimed in claim 2 comprising a third matrix circuit connected to the output side of the multiplex counter circuit, and OR gates connecting the third matrix circuit to the flip-flop circuits for resetting the same, said OR gates further connecting the AND gates to the flip-flop circuits.

6. An electronic musical instrument as claimed in claim 1 comprising a speaker coupled to said gate circuits.

5. An electronic musical instrument as claimed in claim 1 wherein said multiplex counter circuit includes a multivibrator and two binary circuits.

6. An electronic musical instrument as claimed in claim ll comprising an OR gate connecting the switches to said common output connector. 

1. An electronic musical instrument comprising a multiplex counter circuit having an output side, first and second matrix circuits coupled to said output side and including output terminals, key switches, a single common output for said key switches, the output terminals of the first matrix circuit being connected through respective of said key switches to said single common output conductor, a pulse selective circuit, said output conductor and respective of the output terminals of the second matrix circuit being connected to said pulse selective circuit, said pulse selective circuit having an output side, a plurality of gate circuits corresponding to the key switches being connected to the output side of the pulse selective circuit so that if any of the key switches is closed the corresponding gate circuit is opened, and a sound source signal generator coupled to said gate circuit to pass a signal therethrough.
 2. An electronic musical instrument as claimed in claim 1, wherein the pulse selective circuit comprises a plurality of flip-flop circuits connected to respective of the gate circuits, and a plurality of AND gates connected to and supplying inputs to the flip-flop circuits, said common output conductor being connected to the said AND gates, the output terminals of the second matrix circuit being connected to the AND gates in corresponding relationship.
 3. An electronic musical instrument as claimed in claim 2 comprising a third matrix circuit connected to the output side of the multiplex counter circuit, and OR gates connecting the third matrix circuit to the flip-flop circuits for resetting the same, said OR gates further connecting the AND gates to the flip-flop circuits.
 4. An electronic musical instrument as claimed in claim 1 comprising a speaker coupled to said gate circuits.
 5. An electronic musical instrument as claimed in claim 1 wherein said multiplex counter circuit includes a multivibrator and two binary circuits.
 6. An electronic musical instrument as claimed in claim 1 comprising an OR gate connecting the switches to said common output connector. 